EXCOUNT-A
Accessories
Surge Counter EXCOUNT-A
Highest personnel safety
• Explosion-proof for short-circuit currents
up to 80 kA.
• Same safe performance as arresters.
Negligible residual voltage
• Does not reduce protection margins.
• Reduces risk against accidental contact
during surges.
Long life
• Moulded components, non-sensitive to
humidity or temperature variations.
• Verified by tests per IEC 60068.
Universal application
• All makes and types of surge arresters.
• All weather and temperature conditions.
For gapless surge arresters, surge counters are used only to obtain information
regarding surge activities in the corresponding surge arrester and its location.
Surge counter, EXCOUNT-A is designed
therefore, to withstand the same severe
conditions as the arresters without failure.
Design features
EXCOUNT-A comprises basically of an
impulse current transformer with a singleturn primary in the form of an insulated
stranded-copper cable to be connected in
the earth circuit of an arrester. The cable is
provided at both ends with tinned-copper
cable shoes.
The secondary circuit consists of a rectifier, capacitor and an electronic switch
connected to a mechanical counting relay
and is totally moulded in plastic which
makes it ideal for exposed installation. The
complete assembly is then housed in an
elegant vented aluminium casing. A suitable-angled window permits easy reading
of the 6-digit cyclometer-typ counter.
S-1
Edition 5, 2004-10
The principle of operation is shown in
figure 1 on next page.
Performance
The design of the secondary circuit ensures that the counting relay is not energised
for low lightning current impulses which
are insignificant to the arrester capability
and life. The stepping criteria are given in
figure 2 on next side. The current transformer secondary output is sufficient for
driving the counter and external supply
source is not needed.
The single-turn primary ensures that the
voltage drop across the counter, even at
the highest impulse currents encountered
in service, is negligible, leading to added
personnel safety and no increase in the
protection level of the arrester.
Since no gaps or series impedance
are used, there is no risk of internal
arcing and consequent explosive faillure
in the event of a short-circuit following
an arrester failure.
ABB Surge Arresters — Buyer’s Guide
Accessories
EXCOUNT-A
Routine tests
Type tests
EXCOUNT-A has been subjected to severe
electrical, mechanical and climate tests:
Shock test, 15 g
IEC 60068-2-27
Vibration test
IEC 60068-2-6
Temperature test
(-55°C/+70°C)
IEC 60068-2-14
Humidity test
IEC 60068-2-30
Salt fog test
(500h, +35°C,
95%RH, 5% salt)
DIN 50021
Impulse tests
IEC 60099-4
Short-circuit test
(full asymmetry of 2.6)
IEC 60099-4
At 65 kA, there were no damages at all.
At 80 kA, the insulation of the primary
conductor was burnt.
However, the counter function was not
impaired and no pieces were ejected.
All surge counters are routine-tested
with a sufficient number of impulses in a
pass/no pass test prior to despatch from
the factory.
Packing, installation and
maintenance
Counters are packed in cases together
with arresters. For separate supply, they
are packed in cartons.
Detailed instructions are enclosed with
each counter. However, the following may
be noted.
The counter must be placed at a suit
able height for easy reading. The electrical lead between the earth terminal and
the counter should be insulated and its
length kept to a minimum. If the length is
too long, the counter may not register for
very steep impulses when the inductive
voltage between the earth terminal and
the counter exceeds the lightning impulse
withstand level of the insulating base.
The counters are maintenance-free.
Refer to assembly instructions for
more details.
Fig. 1 Schematic diagram
Fig. 2 Stepping criteria
ABB Surge Arresters — Buyer’s Guide
Fig. 3 Dimensions
Edition 5, 2003-10
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